Mast cells play a major role in the inflammatory process through the secretion of substances such as heparin, histamine, prostaglandins, leukotrienes, proteolytic enzymes, and a variety of chemotactic factors. Understanding the nature of the inflammatory response is a central goal of current research in periodontal diseases, yet the role of mast cells in the pathogenesis of these diseases is not well understood. The purpose of the proposed pilot project is to investigate the role of mast cells in the pathogenesis of the inflammatory response associated with experimentally-induced periodontitis, using the mast cell-deficient mouse mutant, W/Wv. Mast cells may have a significant influence on both the early and late stages of both gingivitis and periodontitis, and they may also play a role in the loss of alveolar bone. However, because so many factors are at play during the development of chronic periodontal inflammation, it has been difficult to accurately assess the role of mast cells in diseases of the periodontium. Employment of the mast cell-deficient mutant mouse, W/Wv, represents a promising and unique model system for evaluating the mast cell-mediated contribution to the pathogenesis of both acute and chronic periodontal inflammation. Its normal mast cell-bearing littermate, +/+, provides a positive control for comparing the effects of experimental trauma on periodontal tissues with and without mast cells. The series of pilot experiments outlined in this proposal will investigate the clinical and histologic differences during the development of experimentally induced periodontal inflammation in these animals. In this way, mast cell factors that significantly affect the initiation or progression of periodontal inflammation can be sorted out from factors that are mast cell independent. Development of this model system should lead to a more comprehensive understanding of the influence of mast cells in the progression of inflammatory responses associated with human periodontal diseases.